Node.js Experts in Düsseldorf

Volunteer helper at the Johanniter in medical services and disaster response, highlighting teamwork and coordination even in times of crisis.

• Identification of requirements (legal, organizational, and technical)
• Design of solution architectures
• Evaluation of concepts and technologies
• Preparation of decision templates
• Architectural Decision Records (ADR)
• Coordination of implementation
• Review of implementations
• Documentation

• Contributed to the development of an advanced RAG AI Chat application that integrates multiple LLM models, enabling users to seamlessly switch between models based on specific tasks. This improved the user experience by providing tailored, efficient solutions for various use cases, such as event scheduling, booking systems, and complex task management.
• Participated in designing and implementing a robust backend architecture using Spring AI, enabling advanced AI-driven capabilities like intelligent task automation, language processing, and contextual recommendations. Leveraged Spring AI Tools and Advisors to enhance the performance and decision-making of the AI models.
• Collaborated on the integration of vector databases to support embeddings, enhancing the app's ability to understand user queries and perform actions based on complex, real-time data inputs.
• Contributed to the development of a seamless, user-friendly front-end interface using React with TypeScript support, ensuring a modern, responsive, and scalable user experience across platforms.
• Assisted in implementing state management with Redux RTK for efficient data flow and real-time updates, optimizing the overall user experience in dynamic scenarios such as scheduling and task management.
• Partnered with stakeholders to define feature requirements, helping ensure that the app could scale to meet evolving business needs and integrate with other systems like calendar and email services. Worked alongside cross-functional teams, including data scientists and UI/UX designers, to fine-tune AI models and ensure alignment with project goals.
• Contributed to ensuring end-to-end system performance, security, and compliance by helping integrate authentication mechanisms, role-based access control, and secure communication protocols in both backend and frontend layers.

Technology Stack and Key Contributions:

• Java / Spring Boot / Spring AI: Developed backend services leveraging Spring AI for intelligent responses, task automation, and complex workflows.
• React / TypeScript: Built intuitive user interfaces with React and TypeScript, ensuring a smooth and scalable frontend.
• Redux RTK: Managed application state with Redux RTK for optimized state management, enabling dynamic, real-time data updates.
• Vector Databases: Integrated vector databases (pgVector) for embedding support, improving AI model performance in handling complex queries.
• PostgreSQL / Redis: Managed persistent and temporary data with relational and in-memory data stores, ensuring data integrity and speed.
• Kafka: Utilized Apache Kafka for event-driven communication and seamless integration between microservices.
• Spring Security: Ensured the security of backend services with robust authentication and authorization mechanisms.
• CI/CD & DevOps: Integrated continuous integration and deployment pipelines to ensure rapid and secure deployment of features and updates.

• Responsible for the entire software architecture of the parental allowance portal
• iOS and Android app with React Native and Expo, incl. push and OTA updates
• Store releases via App Store Connect and Google Play Console
• TypeScript monorepo for app, website and backend, web with Next.js and Tailwind
• Own promo, voucher and discount engine with contact and segment logic
• Payments via RevenueCat and in-app purchases, authentication with BetterAuth
• REST APIs based on OpenAPI, PostgreSQL with Prisma and Drizzle
• Self-hosting on Hetzner with Docker, Coolify, Terraform and GitHub Actions
• Tests with Vitest, Playwright and visual regression via Chromatic
• Observability via Grafana Cloud and error tracking with Sentry
• Performance marketing via Meta Ads, measured with custom event tracking
• Grew the product to 20,000 app users with a purchase rate of almost 12 %
• Managing Director since 04.2025, responsible for product and technology

• Migration of backups and complete workloads to AWS and Azure, including setup and management of AKS & EKS clusters.
• Automation with Terraform & ArgoCD, CI/CD pipelines implemented with GitLab.
• System monitoring on OpenShift 4 (on-premise) with Grafana & Prometheus, use of CloudWatch and X-Ray for analysis and logging.
• Building and maintaining secure network infrastructures (VPCs, SGs, WAF, ACLs), integration of Azure Log Analytics.
• Close collaboration with infrastructure and development teams, maintenance of technical documentation with Confluence, ticket handling via Jira, and promoting cloud knowledge within the company.

• Development of a pilot system to control and monitor multiple GoPro cameras
• Implementation of start, stop, status, media, download, and diagnostic functions via COHN endpoints
• Realization of camera detection, single and group control, as well as stable session/keep-alive logic
• Setup of a download pipeline with queue, retry handling, and temporary files
• Consistent session, folder, and file naming for multi-camera recordings
• Integration of provisioning, certificates, and network operations

• Built and launched the AI-powered “E-Invoice Corrector,” an intelligent system for validating and correcting invoices, using Python, FastAPI, and machine learning. The system is now live at Fintom8.
• Converted the Corrector into a fully functional API, published with Swagger documentation for easy access and integration by internal and external consumers.
• Designed, experimented with, and optimized advanced LLM prompts and meta-prompting strategies to improve automated reasoning, error correction, and decision-making in agent workflows.
• Wrapped and integrated existing APIs within the Google Agent Development Kit (ADK) framework to enhance automation capabilities and conversational AI workflows.
• Implemented comprehensive unit testing using pytest and unittest, and employed breakpoint debugging (VS Code, pdb) to ensure code reliability, maintainability, and smooth runtime execution.
• Utilized Pydantic and Tabulate for structured data validation, API schema management, and clear tabular data representation in testing and debugging workflows.
• Pursuing the Google Cloud Professional Certificate.

• Solution architecture & development for a global commerce platform.
• Technologies: Spryker, PHP, AWS, SAP, VueJS

• Third-side integration development (REST: Amazon, OpenAI, Etsy, Shopware, Prestashop, etc)

• Performance optimization (Refactoring, SQL analysis)

• LMS development and deployment (Moodle)

• Cloud deployment automation (Amazon, Azure, Gitlab CI/CD, Docker)

• Backend and Frontend development (Laravel, VueJs)

• Collaboration with partner-developers (national and international)

• Shirtigo GmbH

• GRELLARTIG Digital GmbH

• velpTEC edutainment GmbH

• Design and implementation of a system to control the entire process for new, removal, and exchange operations of electricity meters by external service providers for a utility company

• Automated retrieval of orders and available devices via defined interfaces (e.g. from SAP)

• Orchestration of process steps (assigning meters, processing meter data, sending updated information back to the source system) using a Spring Boot backend

• Provision of a React-based web client for operational tracking and control of orders, e.g. to continue failed process steps or resend notifications

• Setting up and enhancing an international subscription management system

• Migrating and decommissioning a Hybris-SAP system and integrating Zuora

• Implementing numerous interfaces to various systems (external and internal)

• Setting up and improving monitoring with Grafana, Prometheus, and Databricks

• Introducing logging with Loki

• Implementing business requirements using jQuery, Thymeleaf, Spring Boot, Java, Go, and Python

• Adjusting and extending the GitLab CI pipelines

• Setting up and extending infrastructure as code with Terraform and ArgoCD on AWS

• Setting up and running E2E and performance tests

• Expanding the Databricks business intelligence solution to provide various KPIs

• Responsibilities: Architecture, DevOps, development, unit tests, coaching employees and apprentices, E2E, smoke, and integration tests, agile methods consulting (Kanban, Scrum)

• Technologies and methods: Java, Go, Kotlin, Node.js, Spring Boot, SOAP/REST, Quarkus, Thymeleaf, Vaadin, Slack, Jira, Confluence, IntelliJ, GitLab, SQS, Kafka, AWS, Kubernetes, Terraform, Maven, Gradle, GitLab CI, Databricks

• Development of an interactive prototype for the concept of an AI-supported Enterprise Architecture Management tool. The goal was to present complex relationships between IT systems, business processes, and departments in a way that is easy to understand and to support decision-making in the context of IT transformations.

• The prototype combined data-driven analyses with guided questions and interactive visualizations. A central part was the integration of a RAG process to provide domain-specific EAM knowledge in context. The focus was on quick idea validation, user-centered interaction design, and the technical feasibility of a scalable overall concept.

• Design, implementation, and validation of a RAG process for domain-specific EAM knowledge with Python, LangChain, and graph/vector databases (Neo4J, Milvus)

• Business and technical requirements analysis as well as definition of an MVP

• Development of the architecture and technology concept using Angular, Spring Boot, GraphQL, and Kubernetes

• Design of an interaction concept and creation of a brand style guide with Figma

• Development of interactive prototypes with Angular, Konva.js, and TypeScript

• Integration of CI/CD processes with GitLab CI/CD